1. Field of the Invention
The present invention relates to a color cathode ray tube (CRT) and, more particularly, to a color cathode ray tube in which structure of the cathode ray tube is optimally made light and slim.
2. Description of the Related Art
In general, a cathode ray tube is a sort of the widely used display device, which implements an image as electron beams from an electron gun therein hit a phosphor screen in a high pressure vacuum state.
FIG. 1 is a partially sectioned side view showing an interior of a general color CRT
As shown in FIG. 1, a general color cathode ray tube includes: a panel 1 formed with a substantially flat outer surface and an inner surface with a certain curvature; a shadow mask 2 disposed with at a certain interval from the inner side of the panel 1; a funnel coupled to the panel 1; a seal edge line 4 formed at a connecting portion between the funnel 3 and the panel 1; an electron gun 5 mounted at a neck portion of the funnel 3 for emitting electron beams; a deflection yoke 6 encompassing the outer side of the funnel 3; and a reinforcing band 7 installed at a skirt portion 1b of the panel 1 to prevent implosion. S denotes a tube axis.
In the general color CRT constructed as described above, when the electron gun 5 receives an image signal, the electron gun 5 emits an electron beam, and the emitted electron beam is accelerated-focused toward a phosphor screen deposited on an inner surface of the panel 1 by a voltage applied to each electrode of the electron gun 5.
The electron beam is deflected by the deflection yoke 6, and color selecting is performed while the electron beam passes through slots (not shown) formed at the mask, and the phosphor screen is irradiated by the electron beam landing on the phosphor screen 1a at the internal surface of the panel 1.
In this manner, the color CRT has such a principle that an image is formed when electron beams reach the phosphor screen deposited on an inner surface of the panel, and the interior of the CRT is maintained in a high vacuum state so that the electron beams can be smoothly moved.
Because the color CRT is made of glass and its interior is maintained in the high vacuum state, a compression force is applied to the inside of the CRT due to an atmospheric pressure. In this case, the peripheral portion and an edge portion of the CRT receive more vacuum stress than other portions, and thus are very weak in terms of structure.
Presently, in the field of display, the display is necessarily made slim to accomplish reduction of cost, obtaining of an installation space and light weight.
In this respect, however, the lighter and slimmer the color CRT is, the weaker its structural strength is.
FIG. 2 is a schematic view showing deformation of a panel of a conventional color CRT.
As shown in FIG. 2, during a process of evacuation for vacuum, the outer surface of the panel 1 and a body portion 3a of the funnel 3 sag inwardly while a skirt portion 1b of the panel 1 swells to be deformed outwardly as indicated in broken lines.
The thusly deformed portion is recovered to its original state when the reinforcing band 7 is engaged to the skirt portion 1b of the panel 1. The recovery rate at this time is equivalent to the recovery amount by the reinforcing band/sagging degree due to vacuum.
However, the conventional color CRT fails to optimize a width of the reinforcing band and a reinforcing band position, so there is a limitation to make the color CRT lighter and slimmer.